public void Delete(RedBlackNode <Key, Value> z)
{
if (z == null)
{
throw new ArgumentNullException(nameof(z));
}
var y = z;
var desiccate = y.NodeColor;
RedBlackNode <Key, Value> x;
if (z.LeftChild == Sentinel)
{
x = z.RightChild;
Transplant(z, z.RightChild);
}
else if (z.RightChild == Sentinel)
{
x = z.LeftChild;
Transplant(z, z.LeftChild);
}
else
{
y = Minimum(z.RightChild);
desiccate = y.NodeColor;
x = y.RightChild;
if (y.Parent == z)
{
x.Parent = y;
}
else
{
Transplant(y, y.RightChild);
y.RightChild = z.RightChild;
y.RightChild.Parent = y;
}
Transplant(z, y);
y.LeftChild = z.LeftChild;
y.LeftChild.Parent = y;
y.NodeColor = z.NodeColor;
}
if (desiccate == Color.Black)
{
DeleteFixup(x);
}
}
private void Traverse(RedBlackNode <Key, Value> node)
{
if (node.LeftChild != Sentinel)
{
Traverse(node.LeftChild);
}
traverseNumber++;
string b = $"Node {node.Index}, Parent";
if (node.Parent == Sentinel)
{
b += " Sentinel";
}
else
{
b += $" {node.Parent.Index}";
}
if (node.LeftChild == Sentinel)
{
b += ", Left Sentinel";
}
else
{
b += $", Left {node.LeftChild.Index}";
}
if (node.RightChild == Sentinel)
{
b += ", Right Sentinel";
}
else
{
b += $", Right {node.RightChild.Index}";
}
Console.WriteLine(b);
//node.Print();
if (node.RightChild != Sentinel)
{
Traverse(node.RightChild);
}
}
public RedBlackTree()
{
Sentinel = new RedBlackNode <Key, Value>();
Root = Sentinel;
Sentinel.NodeColor = Color.Black;
}
private void DeleteFixup(RedBlackNode <Key, Value> node)
{
while (node != Root && node.NodeColor == Color.Black)
{
if (node == node.Parent.LeftChild)
{
var sibling = node.Parent.RightChild;
if (sibling.NodeColor == Color.Red)
{
sibling.NodeColor = Color.Black;
node.Parent.NodeColor = Color.Red;
LeftRotate(node.Parent);
sibling = node.Parent.RightChild;
}
if (sibling.LeftChild.NodeColor == Color.Black &&
sibling.RightChild.NodeColor == Color.Black)
{
sibling.NodeColor = Color.Red;
node = node.Parent;
}
else
{
if (sibling.RightChild.NodeColor == Color.Black)
{
sibling.LeftChild.NodeColor = Color.Black;
sibling.NodeColor = Color.Red;
RightRotate(sibling);
sibling = node.Parent.RightChild;
}
sibling.NodeColor = node.Parent.NodeColor;
node.Parent.NodeColor = Color.Black;
sibling.RightChild.NodeColor = Color.Black;
LeftRotate(node.Parent);
node = Root;
}
}
else
{
var sibling = node.Parent.LeftChild;
if (sibling.NodeColor == Color.Red)
{
sibling.NodeColor = Color.Black;
node.Parent.NodeColor = Color.Red;
RightRotate(node.Parent);
sibling = node.Parent.LeftChild;
}
if (sibling.LeftChild.NodeColor == Color.Black &&
sibling.RightChild.NodeColor == Color.Black)
{
sibling.NodeColor = Color.Red;
node = node.Parent;
}
else
{
if (sibling.LeftChild.NodeColor == Color.Black)
{
sibling.RightChild.NodeColor = Color.Black;
sibling.NodeColor = Color.Red;
LeftRotate(sibling);
sibling = node.Parent.LeftChild;
}
sibling.NodeColor = node.Parent.NodeColor;
node.Parent.NodeColor = Color.Black;
sibling.LeftChild.NodeColor = Color.Black;
RightRotate(node.Parent);
node = Root;
}
}
node.NodeColor = Color.Black;
}
}
